Silver complex diffusion transfer process using 3-hydroxy-propylene sulphite



United States Patent 3,395,015 SILVER COMPLEX DIFFUSION TRANSFER PROCESS USING 3 HYDROXY PROPYL- ENE SULPHITE Jozef Frans Willems, Wilrijk-Antwerp,, Antoine Theofiel Rasschaert, Berchem-Antwerp, and Louis Maria de Haes, Edegem, Belgium, assignors to Gevaert-Agfa N.V., Mortsel, Belgium, a Belgian company No Drawing. Filed-Sept. 24, 1965, Ser. No. 490,082 Claims priority, application Great Britain, Feb. 26, 1965, 8,479/ 65 Claims. (Cl. 96-29) ABSTRACT OF THE DISCLOSURE Image-receiving material for silver complex diffusion transfer process having 3-hydroxy-propylene sulfite incorporated therein to prevent yellowing with age and diffusion transfer process using the same.

The present invention relates to the application of 3-hydroxy-propylene sulphite for preventing the yellow ing of photographic images produced according to the silver complex diffusion transfer process and to an imagereceiving material containing said 3-hydroxy-propylene sulphite.

According to the conventionally applied embodiment of the silver complex diffusion transfer process the lightsensitive silver halide emulsion material is image-wise exposed and then brought into contact with the imagereceiving material during the development and diffusion transfer. When both materials are separated from each other the image-receiving material still contains a part of the chemical substances applied in the development and diffusion transfer such as developing agent, alkali, sodium sulphite and sodium thiosulphate. The developing agents commonly used, for example hydroquinone and p-monomethylamino phenol hemisulphate, show the disadvantage of being rapidly oxidised when exposed to the air in alkaline medium so that in the white parts of the transfer copies yellow to brown coloured products are formed during storage of said copies.

In order to overcome this disadvantage it is for instance known to subject the copy obtained to an aftertreatment with diluted acid or to rinse the copy immediately after processing. These treatments, however, involve additional processing steps which are not advisable when a quick process is contemplated.

It is also known to counteract the yellowing of photo graphic diffusion transfer copies by incorporating into the image-receiving material alkali-consuming substances. Some of these alkali-consuming substances react but very slowly so that large amounts must be added to the material in order to attain satisfactory results while others react immediately with the alkali and so affect the image formation so that in no way they can be used successfully.

It has now been found that very good results can be attained in preventing the yellowing of finished photographic copies obtained according to the silver complex diffusion transfer process by incorporating 3-hydroxypropylene sulphite as alkali-consuming compound into the image-receiving material used in said process. Apart from the fact that 3-hydroxy-propylene sulphite, even when applied in very small amounts, shows particularly Patented July 30, 1968 "ice good anti-yellowing action without adversely affecting the diffusion transfer image formation it offers the advantage of being very well water-soluble, which is not the case with most of the known alkali-consuming substances which have to be dissolved in appropriate solvents other than water for being incorporated into the image-receiving material.

The present invention provides a photographic silver complex diffusion transfer process according to which an image of an original is produced with improved stability and pictorial quality as to yellowing by development of an image-wise exposed light-sensitive silver halide emulsion layer and diffusion of the undeveloped complexed silver halide from the emulsion layer to an image-receiving material that comprises 3-hydroxy-propylene sulphite where the complexed silver halide is converted in the presence of development nuclei in a silver containing image.

The present invention further provides an image-receiving material for use in a silver complex diffusion transfer process which image-receiving material comprises as anti yellowing agent 3-hydroxy-propylene sulphite.

The 3-hydroxy-propylene sulphite of use according to the present invention may for instance be prepared from glycerol and thionyl chloride according to one of the following procedures.

First procedure.In a reaction vessel provided with a stirrer, a thermometer and a dropping funnel, 73 cc. of glycerol (92 g.1 mole) are placed whereupon 72 cc. of thionyl chloride (118 g.-1 mole) are dropwise added by means of a dropping funnel. Hydrogen chloride es; capes abundantly. The reaction proceeds exothermally (the temperature rises to 50 C.) but as the reaction advances, it becomes endothermic and the temperature falls gradually to 0 C. When all thionyl chloride is added nitrogen is blown through the vessel for expelling the hydrogen chloride as completely as possible. Finally the reaction product is placed for some hours on a boiling water bath in order to remove the last traces of hydrogen chloride (water jet vacuum pump).

The crude product may be distilled through a short vigreux column, at a pressure of about 1 mm. The main fraction boils at 126/1 mm.

Second procedure-In a reaction vessel provided with a stirrer, a reflux condenser, a dropping funnel and a thermometer 73 cc. of glycerol and 50 cc. of dichloroethane are placed. Then 72 cc. of thionyl chloride are gradually added. The formed hydrogen chloride, expelled by the dichloroethane, escapes abundantly and the temperature rises to 60 C. so that the dichloroethane refluxes. Then the reaction becomes endothermic and the temperature falls gradually to 5 C. When all thionyl chloride is added the reaction mixture is refluxed for two more hours. Finally the dichloroethane is evaporated on a boiling water bath while a water. jet vacuum pump is employed.

The crude product may be distilled through a short vigreux column, at a pressure of about 1 mm. The main fraction boils at 126/ 1 mm.

The preparation of 3-hydroxy-propylene sulphite as described above by reaction of glycerol with thionyl chloride The 3-hydroxy-propylene sulphite can be incorporated, in a manner commonly used in photographic processes, into any desired layer of the image-receiving material. For instance it can be incorporated into the support, into a baryta-layer, into an intermediate layer arranged between the image-receiving layer and the support, into the image-receiving layer itself and into a water-permeable top layer coated over the image-receiving layer. The 3- hydroxyapropylene sulphite may be applied to the composing layers of the image-receiving material in any suitable manner, as for example, by dipping the layer under consideration in a suitable solution of the 3-hydroxypropylene sulphite, by spreading or otherwise applying such solution over the surface of the layer, or by incorporating the 3-hydroxy-propylene sulphite into the coatin g composition of the said layer.

The 3 hydroxy-propylene sulphite may be incorporated into the! imagereceiving material in an amount comprised preferably between 0.25 and 4 cc. per sq. m. of material.

The composition of the treating solution in the diffusion transfer process according -to the present invention may be that of the common processing solutions for the silver complex diffusion transfer process that contain the ingredients beneficial or essential to the development and the: diffusion transfer for instance developing substance(s) such as hydroquinone, monomethyl-p-aminophenol sulphate, p-aminophenol, a 3-pyrazolidinone compound such as 1-phenyl-3-pyrazolidinone, complexing agent(s) for the non-developed silver halide such as sodium thiosulphate, sodium thiocyanate and ammonia, alkali, potassium bromide, sodium sulphite, a calcium sequestering compound, black toning agent e.g. l-phenyl-S-mercaptotetrazole or similar products such as those described in British Patents 561,875 and 695,905 etc.

The treating solution must not necessarily contain all of the above ingredients; many of them may be present in the image-receiving material and/or in the light-sensitive material. For instance the developing substances may be incorporated into the image-receiving material and/ or into the light-sensitive material so that the treating solution can be restricted for instance to an alkaline aqueous liquid which is free of developing agents. For diffusion transfer processes wherein the treating liquid is an alkaline solution free of developing agents, the imagereceiving material incorporates hydroquinone and the light-sensitive material comprises a 3-pyrazolidinone derivative may be referred to the French patent specification 1,362,792 and to its patent of Addition 84,190.

For alkalizing the treating liquid basic compounds can be used such as sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, sodium carbonate, sodium phosphate, etc. For a compound which is weak in this respect e.g. sodium phosphate, the amount of anhydrous salt used varies from 50 to 200 g. per litre but in the case of a compound which imparts a high degree of alkalinity for instance sodium hydroxide an amount of from 5 to g. will suffice. One of the advantages of using a treating liquid which is free of developing substance is that the liquid cannot get exhausted by aerial oxidation and consequently that it can be used for a long time before being replaced.

The image-receiving material according to the invention may consist of a support which is impregnated with a substance or substances, such as for example development nuclei, for bringing about the formation of a visible image from the diffusing silver halide complex, and/or a compound or compounds capable of forming such a substance in situ. Preferably, however, the image-receiving material comprises a paper or other flexible support that is coated with one or more additional layers. One of these layers may be the image-receiving layer of nucleicontaining layer that comprises such substances(s) for bringing about the formation of a visible image from the diffusing silver halide complex, and/or such compound(s) capable of forming such substance(s) in situ. Such an image-receiving layer can suitably be prepared from colloid binding agents such as gelatin, mixtures of gelatin and sodium alginate, gelatin and carboxymethyl cellulose, polyvinyl alcohol, partially saponified polyvinyl acetate, cellulose acetate or hydrated colloidal silica wherein the development nuclei are incorporated.

According to the present invention it is also possible to usei an image-receiving material, which contains no substance(s) for bringing about the formation of a visible image from the diffusing silver halide complex, the said substance(s) being present in the treating solution. Such silver halide diffusion transfer process has been described more detailedly in the British patent application 1,001, 8 and in the French patent specification 84,127( which is a patent of addition to the French patent specification 1,321,724), wherein it is carried out with a light-sensitive material bearing a water-permeable colloid layer on top of the light-sensitive layer.

Examples of development nuclei for complexed silver halide which are suitable for being used according to the invention are sulphides, selenides, polysulphides, polyselenides, thioureas, mercaptans, stannous halides, heavy metals or their salts and fogged silver halide. Sulphides of heavy metals such as antimony, bismuth, cadmium, .cobalt, lead, nickel and silver are also suitable. Among the heavy metals silver," gold, platinum, palladium and mercury are to be mentioned, preferably in colloidal form. The noble metals among them are the most active.

The image-receiving material may also comprise in at least one of its layers other ingredients for the diffusion transfer process such as sodium sulphite, a complexing agent for silver halide such as sodium thiosulphate and black-toning agents. It is particularly interesting to have present in the image-receiving material for-instance in the nuclei-containing layer, a quantity of hydroquinone and occasionally at least one compound selected from the group consisting of alkali met abisulphites such as potassium metab-isulphite, water-soluble inorganic bisulphites and water-soluble aldehyde bisulphites. An image-receiving material containing hydroquinone and the said bisulphites is described in the British patent application 1,000, 115. The hydroquinone is suitably present in an amount of from 0.1 to 5 g. per sq. m. and the water-soluble bisulphite in an amount of from 0.2 to 2 g. per sq. m.

The image-receiving layer can also be applied to the same support as the silver halide emulsion layer, for instance as described in the British patent application 1,006,292. The multilayer material described in said patent application comprises a light-sensitive silver halide emulsion layer, an underlying image-receiving layer and between these two layers at least one intervening layer, which consists of or comprises a starch ether. After exposure, development anddiffusion transfer to the image-receiving layer the silver halide emulsion layer can be detached from the starch ether intermediate layer by bringing the imagewise exposed and developed multilayer material in a rinsing bath at room temperature or even at lower temperature whereby the emulsion detaches as a coherent membrane or by other methods such as stripping off after contact with a sheet of paper.

The light-sensitive material suitable for use in the silver complex diffusion transfer process according to the present invention may be any material comprising a lightsensitive silver halide emulsion layer, the exposed silver halide of which is sufficiently rapidly developed and the non-exposed silver halide of which is sufficiently rapidly complexed for allowing the formation of a diffusion transfer image. Preferably gelatino silver chloride emulsions are used, which may contain amounts of silver bromide or silver iodide and to which other ingredients may be added in order to obtain the desired emulsion characteristics. The light-sensitive silver halide emulsion layer may be hardened in a usual way by a suitable hardening agent such as formaldehyde.

Preferably the silver halide emulsion layer contains per sq. m. of light-sensitive material an amount of sil-ver halide equivalent to from 0.2 g. to 2 g. of silver nitrate.

The light-sensitive silver halide emulsion layer of the light-sensitive material may be coated over with a top layer of a water-permeable colloid. Such light-sensitive materials are described e.g. in the British patent specification 1,001,558, in the above French patent of addition 84,127 and in French patent specification 84,190, referred to above. Suitable water-permeable colloids are among others: methyl cellulose, hydroxyethyl cellulose, hydroxyethyl starch, hydroxypropyl starch, sodium alginate, propylene glycol ester of alginic acid, gum tragacanth, starch, poly(vinylalcohol), poly(acrylic acid), poly(acrylamide), poly(v-inyl pyrrolidinone), poly(oxyethylene), copoly(methyl vinyl ether/maleic acid), etc. The most suitable thickness for this top layer depends inter alia on the nature of the colloid chosen and the viscosity of the used colloid solution, but in general the top layer should be only a thin layer.

Into the light-sensitive emulsion layer and/or into a water-permeable layer situated at the same side of the support as the said emulsion layer substances beneficial or essential to the process may be incorporated such as for instance developing agents, softening agents, stabilizing agents, hardening agents, black-toning agents and the like.

Particulars concerning the suitable exposing and developing apparatus as well as the common silver complex diffusion transfer process in general and the materials suitable therefor can be found in Progress in Photography, vol. I, 1940-1950, p. 76, 77 and 140; vol. II, 1951-1954, p. 156-157; vol. III, 1955-1958, p. 24- 36 and the patent literature cited therein.

In carrying out the present invention both the lightsensitive and the image-receiving material may be moistened w-ith treating liquid and then brought into contact with each other. It is, however, also possible to moisten only one of the materials used, preferably the light-sensitive material, and to bring this moistened material into contact with the dry one. This latter embodiment is successfully applied especially when the light-sensitive material is coated over with a top layer of a waterpermeable colloid as described above. The moistening of at least one of the materials used may occur by means of wetted rollers e.g. as fully described in the French patent specification 1,407,079. In this way only one side e.g. the emulsion side of the light-sensitive material is wetted, which is a preferred embodiment. In this patent specification also an interesting method is described of separating the light-sensitive and the image-receiving material from each other. The advantage of wetting only the lightsensitive material, preferably by means of wetted rollers, is that the obtained diffusion transfer copy is practically immediately dry and only a very little quality of treating liquid becomes absorbed.

In order to obtain a completely dry diffusion transfer print the image-receiving material or the pressed sandwich of light-sensitive and image-receiving materials may be subjected to heat. The application of heat may occur in order to accelerate the diffusion transfer and/or to facilitate the separation of the light-sensitive material from the image-receiving material.

Finally, it is also possible, to obtain several diffusion transfer prints from one and the same image-wise exposed light-sensitive material by bringing the latter, in the presence of the treating liquid, successively into contact with a second, a third, etc. image-receiving material.

The following examples illustrate the present invention.

Example 1.-A gelatino silver chloride emulsion hardened in the usual way with formaldehyde is applied at 45 C. to a common paper support of 90 g./sq. m. in such a way that an amount of silver chloride equivalent to 0.7 g. of silver nitrate is present per sq. m. of lightsensitive material. Onto this silver chloride emulsion layer a top layer is coated in a proportion of 1 litre per 20 sq. m. from the following composition:

Water cc Hydroxypropyl starch g 10% solution of 1 phenyl 3 pyrazolidinone in ethanol cc 12% aqueous solution of saponin cc The light-sensitive material thus obtained is image-wise exposed and then moistened with the following treating liquid:

Water cc 1000 Trisodium phosphate g 75 Anhydrous sodium sulphite g 40 Anhydrous sodium thiosulphate g 10 This moistened light-sensitive material is then brought into contact with a dry image-receiving material consisting of a paper support of 90 g./sq. m. to which a layer from the following composition has been applied at 45 C. in a proportion of 1 litre per 25 sq. m.:

Water cc 844 Gelatin g 20 Colloidal silver g 0.01 Hydroquinone g 25 Potassium metabisulphite g 25 20% aqueous solution of formaldehyde cc 40 3-hydroxy-propylene sulphite cc 20 Water cc 864 Gelatin g 20 Colloidal silver g 0.01 Hydroquinone g 25 Potassium metabisulphite g 25 20% aqueous solution of formaldehyde cc 40 This suspension is applied in such a way that 1 litre covers 25 sq. m.

Example 3.-While thoroughly stirring 5 cc. of 3-hydroxy-propylene sulphite are added to a suspension of 28 g. of barium sulphate in cc. of a 2% aqueous gelatin solution. This suspension is applied to a paper support. Then said barium sulphate layer is coated pro rata of 13 sq. m./litre with a nuclei-containing layer of the following composition:

Water cc 925 Gelatin g 33 Sodium thiosulphate (cryst.) g 40 Sodium sulphide g 0.2 Cobaltous nitrate 6 aq. g 1

The image-receiving material thus obtained is dried.

A light-sensitive material is prepared by coating a paper support of 90 g./sq. m. with a gelatino silver chloride emulsion layer in such a way that an amount of silver chloride equivalent to 1 g. of silver nitrate is present per sq. m. of light-sensitive material.

The light-sensitive material is image-wise exposed and then together with the image-receiving material fed through a diffusion transfer processing apparatus that contains a solution of the following composition:

Sodium hydroxide g 11 Sodium sulphite (anhydrous) g 100 Potassium bromide g 1.5 Hydroquinone g 9 1-phenyl-3-pyrazolidone g 1.5 Water up to cc 1000 The light-sensitive material and the image-receiving material are pressed against each other by the rubber rollers of the processing apparatus. After a short contact period the materials are separated from each other. A positive print of the original is obtained that keeps its white background even after storing for a long time.

Example 4.Example 3 is repeated using, however, an image-receiving material prepared in the following way. A nuclei-containing layer is applied from the following composition to a paper support:

Water cc 210 Crystalline sodium thiosulphate g 10 Gelatin g 12.5 Colloidal silver sulphide g 0.01

To this nuclei-containing layer a top layer is applied from a 3% aqueous solution of carboxymethyl cellulose comprising 5 cc. of 3-hydroxy-propylene sulphite.

The positive print obtained shows no stains after storing for a long time.

Example 5.A paper support is impregnated with a aqueous solution of 3-hydroxy-propylene sulphite. Then a nuclei-containing layer as described in Example is applied to the paper base.

A light-sensitive material is prepared by coating a paper support of 90 g./sq. m. with a gelatino silver chloride emulsion layer in such a way that an amount of silver chloride equivalent to 1.3 g. of silver nitrate is present per sq. m. After exposure, development and diffusion transfer as described in Example 3 a positive image is obtained that keeps its white background even after storing for a long time.

What we claim is:

1. Method for producing photographic images according to the silver complex diffusion transfer process comprising the steps of (1) image-wise exposing a light-sensitive material containing a silver halide emulsion layer,

(2) contacting the light-sensitive material in the presence of a developing agent, a complexing agent for silver halide alkali and an aqueous treating liquid with an image-receiving material having incorporated thcrein 3-hydroxy-propylene sulphite, whereby the diffusion transfer image forms in the presence of development nuclei, and

(3) separating the light-sensitive material from the image receiving material.

2. Method for producing photographic images according to the silver complex diffusion transfer process comprising the steps of (1) image-wise exposing a light-sensitive material containing a silver halide emulsion layer,

(2) wetting the image-wise exposed light-sensitive material with an aqueous treating liquid,

(3) bringing the wetted light-sensitive material in the presence of a developing agent, a complexing agent for silver halide and alkali into contact with a dry image-receiving material containing 3-hydroxy-propylene sulphite, whereby the diffusion transfer image forms in the presence of development nuclei, and

(4) separating the light-sensitive material from the image-receiving material.

3. Method for producing photographic images according to the silver complex diffusion transfer process comprising the steps of (1) image-wise exposing a light-sensitive material containing a silver halide emulsion layer,

(2) wetting only the emulsion side of the image-wise exposed light-sensitive material with an aqueous treating liquid,

(3) bringing the wetted light-sensitive material in the presence of a developing agent, a complexing agent for silver halide and alkali into contact with a dry image-receiving material containing 3-hydroxy-propylene sulphite, whereby the diffusion transfer image forms in the presence of development nuclei, and

(4) separating the light-sensitive material from the image-receiving material.

4. Method for producing photographic images according to claim 1, wherein the light-sensitive material and the image-receiving material are held in contact with each other whilst heat is supplied.

5. Method for producing photographic images according to claim 1, wherein the developing agent is present in one of the light-sensitive and image-receiving material.

6. Method for producing photographic images according to claim .1, wherein the silver halide emulsion layer of the light-sensitive material has been coated over with a water-permeable colloid layer.

7. Image-receiving material for use in a method for producing photographic images according to the silver complex diffusion transfer process, wherein 3-hydroxypropylene sulphite is incorporated therein.

8. Image-receiving material according to claim 7 including a support and wherein the 3-hydroxy-propylene sulphite is incorporated into the support.

9. Image-receiving material according to claim 7 including a baryta-layer and wherein the 3-hydroxy-propylene sulphite is incorporated into a baryta-layer coated on the support.

10. Image-receiving material according to claim 7 including an image-receiving layer and wherein the S-hydroxy-propylene sulphite is incorporated into the imagereceiving layer.

11. Image-receiving material according to claim 7, including a water-permeable top layer coated over an image-receiving layer and wherein the 3-hydroxy-propylene sulphite is incorporated into said top layer.

12. Image-receiving material according to claim 7 and containing hydroquinone.

13. Image-receiving material according to claim 12, wherein the hydroquinone is present in an amount of from 0.1 to 5 g. per sq. m. of the image-receiving material.

14. Image-receiving material according to claim 12 and containing an alkali metabisulphite, a water-soluble inorganic bisulphite or a water-soluble aldehyde bisulphite.

15. Image-receiving material according to claim 14, wherein the water-soluble bisulphite is present in an amount of from 0.2 to 2 g. per sq. m. of the image-receiving material.

References Cited 

